Optically active (non-racemic) epoxy alcohols such as (R)- and (S)- glycidol are extremely useful and versatile starting materials and intermediates in the synthesis of chiral natural products and natural product analogues or derivatives. Many such optically active products derived from chiral epoxy alcohols have a high physiological activity and thus are of great interest in the pharmaceutical field. The synthetic utility of non-racemic epoxy alcohols has been extensively reviewed in Hanson, Chemical Reviews 91(4), 437-473 (1991).
Recently, the preparation of optically active epoxy alcohols from inexpensive racemic starting materials such as allylic alcohols has become feasible on a commercial scale due to the development of an asymmetric epoxidation method by Dr. K. Barry Sharpless and co-workers wherein an allylic alcohol is reacted with an organic hydroperoxide in the presence of a titanium/chiral carbinol complex catalyst. While this method affords good yields of epoxy alcohol having high optical purity, recovery of the epoxy alcohol from the crude epoxidation reaction mixture is not simple due to the number of different substances present (typically, epoxy alcohol, unreacted allylic alcohol, unreacted hydroperoxide, organic solvent, the alcohol derived from reduction of the hydroperoxide during epoxidation, and catalyst are all present). In addition, glycidol and related compounds are notoriously unstable and reactive. Significant losses due to polymerization, ring-opening (e.g., hydrolysis or alcoholysis), acid-catalyzed or thermal decomposition, and the like are often encountered during purification of these substances.
The development of improved methods whereby optically active glycidol or the like may be isolated from an asymmetric epoxidation reaction mixture in high yield with minimal loss of optical purity would therefore be of considerable value.